Antibiotics – Mechanism of Action, Compatibility, Dosage Rules

Antibiotics – Mechanism of Action, Compatibility, Dosage Rules

Antibiotics are medications derived from bacteria. They initiate a process called antibiosis, where living cells suppress the activity of other living cells. This can harm not only infectious agents but also tissues of the body.

Such a mechanism of action evokes mixed feelings towards these drugs. Some are hesitant to take them, fearing potential harm. Others view them as a cure-all, consuming them indiscriminately and then being surprised by the lack of results or side effects.

Understanding how antibiotics work can help avoid such extremes. In this article, you will learn about the diseases they are used to treat and how to use them safely.

Why Take Antibiotics?

Since these drugs are antibacterial, they are only used to treat bacterial infections. This means taking them for viral or fungal agents is pointless. The reasons for this include:

  • All other microorganisms, except bacteria, are not susceptible to them.
  • Beneficial bacteria necessary for normal bodily functions may be harmed.
  • There is a risk of developing resistance, which may render antibiotic therapy ineffective even against bacterial infections.

Therefore, the main rule is to take antibiotics exclusively for the treatment of bacterial diseases. Only a doctor can determine the nature of the pathology based on laboratory tests. So, without diagnosis and specific prescription, it’s best to avoid such medications.

How Do Antibacterial Agents Work?

They identify bacteria and attack them. The therapeutic effect can be achieved in various ways, so pharmacologists classify antibiotics based on their mode of action:

  • Bactericidal: destroy bacteria.
  • Bacteriostatic: prevent their growth and reproduction.
  • Narrow-spectrum: target only gram-positive or gram-negative microorganisms.
  • Broad-spectrum: attack any bacteria.

However, these agents cannot accurately discern which bacteria are harmful to the body and which are necessary. Consequently, side effects often occur, caused by dysbiosis. Typically, the digestive system reacts, less frequently the skin and central nervous system (CNS).

Hence, the second important rule is to always conduct dysbiosis prevention alongside antibacterial therapy. Here, the involvement of a doctor is crucial.

Other Rules for Taking Antibiotics

Adhering to the first two rules largely eliminates potential harm from antibacterial therapy for adults. However, achieving therapeutic effects requires more:

  • Adhering to the duration of treatment. Even if visible improvements occur, discontinuing treatment is not advisable. Otherwise, pathogenic microorganisms may become active again.
  • Not adjusting doses independently. Only a doctor can determine the correct dosage for a specific case.
  • Following the instructions. It specifies whether to take the medicine before or after meals. Some require more gastric juice for absorption, so they should be taken on an empty stomach, while others irritate the mucous membrane, so it’s better to take them with food.

Also, consider the time of day. It’s better to clarify with the doctor whether to take a particular medication during the day or evening. However, many antibiotics are recommended to be taken in the evening.

Compatibility of Antibiotics

These tablets or capsules should only be taken with water. Milk contains calcium, which neutralizes the antibacterial effect. Tea and coffee containing tannin and caffeine also lead to undesirable reactions.

Often, other medications, including those for treating chronic diseases, need to be taken alongside antibiotics. However, they are not compatible with all pharmacological agents. Prohibited combinations include:

  • Antacids (agents to reduce stomach acidity).
  • Hormonal contraceptives.
  • Calcium-containing preparations.
  • Vitamins B and C.
  • Anticoagulants (blood-thinning medications).

When prescribing treatment, it’s necessary to inform the doctor of the need to take a particular medication, recommended duration of the course, and diagnosis. They will decide on the correct course of action in the given situation and may involve a colleague who prescribed the incompatible medication.

Antibiotics for Children

Pediatricians rarely prescribe these drugs to children due to the peculiarities of their bodies. The harm from their effects may outweigh the expected benefits. They are prescribed only in serious cases:

  • Streptococcal or staphylococcal angina with a temperature rise to 40 degrees Celsius.
  • Lymphadenitis caused by bartonella infection.
  • Pneumonia caused by streptococcus or haemophilus.
  • Acute pyelonephritis caused by E. coli.
  • Abscess in the space between the tonsil and pharyngeal muscles (usually streptococcal).

In such diagnoses, there is a threat to the child’s life, and eliminating it is more important than preventing side effects. Such treatment often leads to dysbiosis, necessitating concurrent administration of prebiotics and probiotics. The former promote the growth of new microflora, while the latter help restore existing microflora.


Antibacterial therapy is not a solution to all problems, as demonstrated by the situation with the coronavirus. Ideas about treating it with antibiotics were often voiced, but there were no results. These drugs only deal with bacterial infections and nothing more.

There’s no need to fear such therapy. Doctors prescribe these medications only when absolutely necessary. Knowing how to take antibiotics correctly will not cause significant harm. Simply follow medical recommendations regarding:

  • Duration of the course.
  • Time of intake (morning or evening).
  • Dosage.
  • Compatibility.

Since the side effects of antibacterial treatment are well-known, doctors take preventive measures immediately. They prescribe remedies to prevent dysbiosis and liver damage. Therefore, antibiotics can be taken by both adults and children.